In wireless radio access networks, reference signals may be transmitted to facilitate communications between network devices, e.g., base stations, user equipments. The reference signals are known to both the transmitter and the receiver for channel measurement, information demodulation, and the like. The reference signals may also be referred to as pilot signals.
Multi-antenna technologies are frequently used in communication systems to increase transmission data rate and spectral efficiency. Various multi-antenna technologies may be adopted for multi-antenna systems, e.g., spatial multiplexing, transmit diversity, cyclic-delay diversity, or the like. When multiple antennas are employed, reference signals may be transmitted for each transmit antenna such that channels corresponding to each transmit antenna may be measured.